Consistency of selected craniometric landmark locations and the resulting variation in measurements.

Recently, forensic anthropology has undergone a major shift to quantitative methodologies, including the standardization of osteometric measurements. This study is an analysis of inter-observer error rates for eight "standardized" cranial measurements. Thirty participants, of varied experience, were asked to note the location of landmarks used in each measurement, and to record the resulting measurement. None of the tested measurements met the previously established 80% consensus rate necessary to be considered "standardized-in-practice" [1]. The highest consensus rate was that of nasal breadth (67.9%), followed by that of the mastoid height (57.1%). This low precision yielded percent mean differences of 2-48% of the total measurement, with range differences of up to 42mm. These results indicate that the field should take steps to improve osteometric standardization, including re-examining all measurements currently listed in osteometric canon and re-issuing a comprehensive guide.

How "standardized" is standardized? A validation of postcranial landmark locations.

Since the mid-1990s, osteometrics have been a major aspect in forensic anthropology. However, recent evidence has shown that practitioners have been using differing points to establish certain measurements; namely those involving the clavicle, scapula, ulna, femur, and tibia. Engaging 61 practitioners, this study examined and confirmed how extensive this discord is. The highest consistency rate among practitioners was the scapular breadth (62.3%), followed by the femoral anteroposterior subtrochanteric diameter (55%). All other levels fell below these, particularly the physiological length of the ulna which was the most inconsistently measured bone. Furthermore, these low consistency rates yielded percent mean differences between two and 20% of the measurement length, with ranges averaging 14 mm. In light of these results, it is recommended that the field take steps to improve the standardization of such problematic measurements, including reexamining all measurements currently listed in osteometric texts, reassessing the utility of each, and reissuing a comprehensive guide.

The temporal degradation of bone collagen: A histochemical approach.

As forensic anthropologists are currently unable to estimate reliably and quantitatively the postmortem interval (PMI) of skeletonized remains, the current study was conducted to determine if degradation of bone collagen over time could be quantified using sirius red/fast green staining, and whether the degradation would occur at a predictive rate such that it may be used to estimate the PMI of skeletonized individuals. Resin embedded 200-300µm cross-sections of pig (Sus scrofa) long bones with known provenience and PMIs ranging from fresh to 12 months were stained using a histochemical reaction which differentially stains collagenous (Co) and non-collagenous (NCo) proteins. Spectrophotometry was used to determine the concentration of Co and NCo proteins in each bone section, after which the ratio of these proteins was calculated. The results of this study revealed a significant decline in the ratios of Co/NCo protein concentrations over the time period studied (p<0.001). Furthermore, a significant negative correlation between the ratios of Co/NCo protein concentrations and time (r=-0.563, p<0.0001) was observed. Despite a significant correlation, the moderate r-value obtained suggests that, at present, this method is useful primarily for detecting and quantifying the degradation of Co and NCo proteins in bones. Future studies that include shorter time intervals and environmental factors, such as soil pH, temperature, and hydrology may prove to be critical for using this method for PMI estimation.